Bank Phase Current Unbalance Settings - GE C70 Instruction Manual

SETTINGS EXAMPLE
The 87V-2 and 87V-3 differential elements for the strings against tap voltage are created in a similar manner. In these
cases, the K factor is different, reflecting the voltage division of K = 463.8194 between the string and tap capacitor
voltages.

8.4.6 Bank phase current unbalance settings

Two phase current unbalance (ANSI 60P) stages are used to provide trip and alarm levels during capacitor unit failures in
each differential element.
The pickup setting for the stage 1 phase current unbalance alarm element is programmed for one element failure.
Therefore, the alarm delay is specified as 10 seconds. The following setting values are programmed in the EnerVista UR
Setup software.
8
8-18
Figure 8-13: Voltage differential blocking during VT fuse failure
SRC2 VT FUSE FAIL OP
OR(2)
SRC3 VT FUSE FAIL OP
OR(2)
= VTFF 87V-1 (VO1)
SRC1 VT FUSE FAIL OP
OR(2)
SRC2 VT FUSE FAIL OP
OR(2)
= VTFF 87V-2 (VO2)
SRC1 VT FUSE FAIL OP
OR(2)
SRC3 VT FUSE FAIL OP
OR(2)
= VTFF 87-3 (VO3)
60P alarm = 0.9I
unbal f1_max ( )
C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL
CHAPTER 8: APPLICATION OF SETTINGS
= VTFF 87V-1 (VO1)
= VTFF 87V-2 (VO2)
= VTFF 87V-3 (VO3)
843765A1.CDR
= 0.9 0.0209 pu × = 0.019 pu Eq. 8-25